feat($interval): add a service wrapping setInterval

The $interval service simplifies creating and testing recurring tasks.
This service does not increment $browser's outstanding request count,
which means that scenario tests and Protractor tests will not timeout
when a site uses a polling function registered by $interval. Provides
a workaround for #2402.

For unit tests, repeated tasks can be controlled using ngMock$interval's
tick(), tickNext(), and tickAll() functions.

1 files changed, 90 insertions, 0 deletions

diff --git a/src/ng/interval.js b/src/ng/interval.js
new file mode 100644
index 00000000..e612f3e4
--- /dev/null
+++ b/src/ng/interval.js
@@ -0,0 +1,90 @@
+'use strict';
+
+
+function $IntervalProvider() {
+  this.$get = ['$rootScope', '$window', '$q',
+       function($rootScope,   $window,   $q) {
+    var intervals = {};
+
+
+     /**
+      * @ngdoc function
+      * @name ng.$interval
+      *
+      * @description
+      * Angular's wrapper for `window.setInterval`. The `fn` function is executed every `delay`
+      * milliseconds.
+      *
+      * The return value of registering an interval function is a promise. This promise will be
+      * notified upon each tick of the interval, and will be resolved after `count` iterations, or
+      * run indefinitely if `count` is not defined. The value of the notification will be the
+      * number of iterations that have run.
+      * To cancel an interval, call `$interval.cancel(promise)`.
+      *
+      * In tests you can use {@link ngMock.$interval#flush `$interval.flush(millis)`} to
+      * move forward by `millis` milliseconds and trigger any functions scheduled to run in that
+      * time.
+      *
+      * @param {function()} fn A function that should be called repeatedly.
+      * @param {number} delay Number of milliseconds between each function call.
+      * @param {number=} [count=0] Number of times to repeat. If not set, or 0, will repeat
+      *   indefinitely.
+      * @param {boolean=} [invokeApply=true] If set to `false` skips model dirty checking, otherwise
+      *   will invoke `fn` within the {@link ng.$rootScope.Scope#$apply $apply} block.
+      * @returns {promise} A promise which will be notified on each iteration.
+      */
+    function interval(fn, delay, count, invokeApply) {
+      var setInterval = $window.setInterval,
+          clearInterval = $window.clearInterval;
+
+      var deferred = $q.defer(),
+          promise = deferred.promise,
+          count = (isDefined(count)) ? count : 0,
+          iteration = 0,
+          skipApply = (isDefined(invokeApply) && !invokeApply);
+
+      promise.then(null, null, fn);
+
+      promise.$$intervalId = setInterval(function tick() {
+        deferred.notify(iteration++);
+
+        if (count > 0 && iteration >= count) {
+          deferred.resolve(iteration);
+          clearInterval(promise.$$intervalId);
+          delete intervals[promise.$$intervalId];
+        }
+
+        if (!skipApply) $rootScope.$apply();
+
+      }, delay);
+
+      intervals[promise.$$intervalId] = deferred;
+
+      return promise;
+    }
+
+
+     /**
+      * @ngdoc function
+      * @name ng.$interval#cancel
+      * @methodOf ng.$interval
+      *
+      * @description
+      * Cancels a task associated with the `promise`.
+      *
+      * @param {number} promise Promise returned by the `$interval` function.
+      * @returns {boolean} Returns `true` if the task was successfully canceled.
+      */
+    interval.cancel = function(promise) {
+      if (promise && promise.$$intervalId in intervals) {
+        intervals[promise.$$intervalId].reject('canceled');
+        clearInterval(promise.$$intervalId);
+        delete intervals[promise.$$intervalId];
+        return true;
+      }
+      return false;
+    };
+
+    return interval;
+  }];
+}